This project focuses upon the different clinical forms of leishmanial infections in humans, immune responses to the parasite, with particular reference to cell-mediated responses and the cytokine regulation of these responses, and characteristics of the causative parasites. Of the 12 patients referred to NIH and cultured for leishmania, only 4 were positive and treated. No explanation could be found for the striking increase in serum lipase and amylase that occurred in association with pentavalent antimony treatment. Tests of cell-mediated immune function (delayed hypersensitivity skin tests and lymphocyte proliferation assays) were carried out in a total of more than 50 Persian Gulf military returnees. No completely satisfactory method of retrospective immunologic diagnosis of leishmanial infection was found for this group of patients, although a number of suggestive cases were identified. Further semi-quantitative assays for mRNA of various cytokines in the bone marrow of visceral leishmaniasis patients are planned. A controlled clinical trial of topical therapy for cutaneous leishmaniasis in Honduras is under evaluation.